Battery modules for automobiles such as electric automobiles or hybrid automobiles include a cell group in which a plurality of cells are arranged in a row. Each of the cells forming the cell group has a positive electrode terminal and a negative electrode terminal, and the electrode terminals having opposite polarities respectively included in adjacent cells are electrically connected by a metal bus bar.
The bus bar is attached to each pair of such electrode terminals at a plurality of locations on the cell group. Such a bus bar is used to electrically connect the cells forming the cell group in series.
If the bus bar is attached to each pair of electrode terminals in the cell group, the attachment operation takes an extensive amount of time. Accordingly, a battery wiring module is used that can simultaneously position a plurality of bus bars on the respective pairs of electrode terminals as shown in JP 2011-8957A and so on. This sort of battery wiring module is configured such that a plurality of bus bars are held by an insulating substrate made of a resin or the like, and is placed on and fixed to the cell group.
If the number of cells contained in a cell group is too large, attachment errors and the like of the electrode terminals may accumulate, and pitches between the electrode terminals having opposite polarities may be larger or smaller than the allowable range. If the above-described battery wiring module is used in this state, it may be rather difficult to attach the bus bars to the respective pairs of electrode terminals. Accordingly, in the above-described battery module, all cells may not be treated as one cell group, but they may be used in a state of being divided into a plurality of cell groups. Furthermore, the cells may be divided into a plurality of cell groups also due to limited space in which the battery module is to be installed, for example.
Note that the plurality of cell groups is electrically connected to each other by dedicated bus bars. Both ends of this sort of bus bar are fixed by bolting or the like respectively to electrode terminals having opposite polarities. The bus bar extends to link the cell groups in a state where both ends are fixed.